A hand job is stimulating the penis with your hand in order to bring pleasure. A guy can do it himself (see: masturbation) or you can give your lover a hand job.
The basic technique is wrapping your hand around the penis and moving it up and down, stimulating (part of ) the shaft and the tip of the penis.
You’re moving your hand from the base to the tip and back again. The main movement is to pull (the movement away from the body) and not to push. Have a firm grip. Most girls are too careful and don’t apply enough pressure.
Only let someone give you a hand job when you are completely ready for it. Never have it done because your girl- or boyfriend takes initiative and you don’t dare to object.
Sensitive spots
Building tension
Tips

Different techniques:
Two hands & milking
Thumbs up & ball trick
Nuzzling up
Making fire

When I give my boyfriend a hand job do I stand or sit down?
When you give a guy a hand job does it make a difference whether he is circumcised or not?
I am afraid to give my boyfriend a hand job